fix: correct stale highspy→highsbox error message; update release announcement for 1.17.1

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: h-g-s

RELEASE-ANNOUNCEMENT.md

@@ -1,12 +1,59 @@
-# python-mip 1.17 Released 🎉
+# python-mip 1.17.1 Released 🎉
 
-We are pleased to announce the release of **python-mip 1.17**, the first new release since
-1.15.0. This version brings a new solver backend, major infrastructure improvements, and several
-bug fixes.
+We are pleased to announce the release of **python-mip 1.17.1**, the first publicly available
+release in quite some time. This is a patch release on top of 1.17, which itself brought a new
+solver backend, major infrastructure improvements, and several bug fixes. 1.17.1 delivers
+important stability fixes for CBC and updated binaries via `cbcbox 2.910`.
 
 ---
 
-## What's New
+## What's New in 1.17.1
+
+### CBC crash fix: Gomory Mixed-Integer cuts (`CutType.GMI`)
+
+A crash was discovered when using `CutType.GMI` with recent CBC versions. The root cause was
+a bug in `scaleCutIntegral` — a function shared by `OsiCuts` and `CglGomory` — that modified
+coefficient arrays **in place** before asserting integrality, causing an `abort()` when
+borderline floating-point rounding left a value just outside the 1e-9 tolerance. The fix
+(pre-check all values before applying any modification) was committed directly to the upstream
+COIN-OR repositories [coin-or/Osi](https://github.com/coin-or/Osi) and
+[coin-or/Cgl](https://github.com/coin-or/Cgl) and is included in `cbcbox 2.910`.
+
+### Updated CBC binaries via `cbcbox 2.910`
+
+python-mip 1.17.1 requires `cbcbox>=2.910`, which ships binaries built from the latest
+COIN-OR master (post-fix). The new wheels include:
+
+- The `scaleCutIntegral` crash fix in both Osi and Cgl
+- Updated `CutType` C enum (`CT_LaGomory` removed; entries renumbered) correctly reflected
+  in python-mip's `ffi.cdef`
+- Performance improvements from recent COIN-OR master commits
+
+### cbcbox: faster CBC, simpler releases
+
+`cbcbox` is now the sole distribution channel for CBC binaries. This decoupling means future
+CBC improvements — algorithm enhancements, bug fixes, new COIN-OR master commits — can reach
+users with a `cbcbox` release alone, without touching python-mip at all. The release cycle
+for CBC upgrades is now:
+
+1. Push fix to upstream COIN-OR (coin-or/Cbc, coin-or/Cgl, coin-or/Osi, …)
+2. Bump `cbcbox` version and push — CI builds all platforms automatically
+3. Bump `cbcbox>=X.Y` in python-mip `pyproject.toml` and push a tag
+
+On x86\_64 (Linux, macOS, Windows), `cbcbox` ships **two** complete solver stacks per wheel:
+
+| Variant | OpenBLAS kernel | Description |
+|---|---|---|
+| `generic` | `DYNAMIC_ARCH` runtime dispatch | Compatible with any x86\_64 CPU |
+| `avx2` | `HASWELL` 256-bit AVX2/FMA | Optimised for Haswell (2013+) and newer |
+
+The best variant is selected automatically at import time. The AVX2 build delivers measurable
+speedups on modern hardware thanks to wider SIMD in the dense linear algebra kernels used by
+Clp's simplex solver.
+
+---
+
+## What's New in 1.17 (first release since 1.15.0)
 
 ### HiGHS is now a supported solver
 
@@ -15,7 +62,8 @@ open-source LP/MIP solver with an MIT licence. HiGHS joins CBC and Gurobi as a f
 backend. It supports LP and MIP solve, warm-starting for LP re-solves, and the full
 python-mip constraint/variable API.
 
-To use HiGHS, install the optional dependency:
+HiGHS binaries are distributed via `highsbox`, installed automatically as an optional
+dependency:
 
 ```
 pip install mip[highs]
@@ -25,52 +73,48 @@ This work was led primarily by **Robert Schwarz**, with contributions from **Tú
 **Adeel Khan**, **Bernard Zweers**, and **Miguel Hisojo**. The integration spanned many months
 of careful incremental work — thank you all!
 
-### CBC binary distribution: a new era with `cbcbox`
+### CBC binary distribution via `cbcbox`
 
-One of the longest-standing pain points in python-mip has been shipping up-to-date CBC binaries.
-Historically, pre-built `.so`/`.dylib`/`.dll` files lived directly in the python-mip repository,
-which meant updating CBC required a full python-mip release and manually building binaries for
-each platform.
+Historically, pre-built CBC binaries lived directly in the python-mip repository, requiring
+a full python-mip release for every CBC update and manual cross-platform builds.
 
-**With 1.17, we have completely decoupled CBC binary distribution** into a new companion package,
-[cbcbox](https://pypi.org/project/cbcbox/). `cbcbox` ships pre-built CBC wheels for:
+**With 1.17, CBC binary distribution is fully decoupled** into
+[cbcbox](https://pypi.org/project/cbcbox/), a dedicated companion package with pre-built
+wheels for:
 
 - Linux x86\_64 and aarch64
 - macOS x86\_64 and arm64 (Apple Silicon, native — no Rosetta!)
 - Windows x64
 
-`cbcbox` is installed automatically as a dependency of python-mip. Future CBC upgrades can now
-be shipped by releasing a new `cbcbox` version — completely independently of python-mip.
-
-A big thank you to **Túlio Toffolo** for also building the first macOS ARM64 CBC binary for the
-transition period, and for co-developing the `cbcbox` tooling.
+`cbcbox` is installed automatically. The same architecture applies to HiGHS via `highsbox`.
 
 ### Automated releases via GitHub Actions
 
-Starting with this release, publishing a new version of python-mip to PyPI is as simple as
-pushing a version tag:
+Publishing a new version of python-mip to PyPI is now as simple as:
 
 ```
-git tag v1.17 && git push --tags
+git tag v1.17.1 && git push --tags
 ```
 
-A GitHub Actions workflow using OIDC Trusted Publisher takes care of building and uploading
-to PyPI automatically, with no API tokens to manage.
+A GitHub Actions workflow using OIDC Trusted Publisher handles building and uploading to
+PyPI with no API tokens to manage.
 
-### Python 3.10–3.13 + PyPy 3.11 support; minimum raised to 3.10
+### Python 3.10–3.13 + PyPy 3.11; minimum raised to 3.10
 
-python-mip now officially supports Python 3.10, 3.11, 3.12, 3.13 and PyPy 3.11, tested across
-Linux (x86\_64 and arm64), macOS (Apple Silicon), and Windows. Python 3.8 and 3.9 have reached
-end-of-life and are no longer supported.
+python-mip now officially supports Python 3.10, 3.11, 3.12, 3.13 and PyPy 3.11, tested
+across Linux (x86\_64 and arm64), macOS (Apple Silicon), and Windows. Python 3.8 and 3.9
+have reached end-of-life and are no longer supported.
 
 ---
 
-## Bug Fixes
+## Bug Fixes (cumulative 1.17 + 1.17.1)
 
-- **CBC re-solve correctness**: Calling `optimize()` multiple times on the same model could
-  return stale results due to a behavioural change in newer CBC. Fixed.
+- **GMI cut crash** (`CutType.GMI`): `scaleCutIntegral` assert in Osi/Cgl. Fixed upstream.
+- **CBC re-solve correctness**: `optimize()` called multiple times could return stale results.
+  Fixed by calling `Cbc_reset()` before each solve.
 - **Empty `LinExpr` in constraints** handled correctly (thanks **Sebastian Heger**, #237).
 - **Windows DLL loading** fixed for Python 3.8+ (`os.add_dll_directory` now used).
+- **Stale HiGHS error message** corrected to reference `highsbox` instead of `highspy`.
 
 ---
 
@@ -99,4 +143,4 @@ Thank you to everyone who contributed code, bug reports, and reviews since 1.15:
 
 Full changelog: https://github.com/coin-or/python-mip/blob/master/CHANGELOG.md
 
-PyPI: https://pypi.org/project/mip/1.17/
+PyPI: https://pypi.org/project/mip/1.17.1/

mip/highs.py

@@ -686,8 +686,8 @@ class SolverHighs(mip.Solver):
     def __init__(self, model: mip.Model, name: str, sense: str):
         if not has_highs:
             raise FileNotFoundError(
-                "HiGHS not found."
-                "Please install the `highspy` package, or"
+                "HiGHS not found. "
+                "Please install the `highsbox` package (pip install mip[highs]), or "
                 "set the `PMIP_HIGHS_LIBRARY` environment variable."
             )